1. Field of the Invention
The present invention relates to a process and to a system for delivering energy to several fluids and simultaneously for mixing them, one of the fluids being miscible in the other fluid or fluids.
2. Description of the Prior Art
The prior art describes various solutions for eliminating acid gases.
One solution consists in injecting the acid gases individually into a reservoir by using centrifugal or reciprocating compressors.
Another procedure consists in injecting the acid gases with another fluid, for example the formation water available in the reservoir. This solution notably has the advantage of eliminating simultaneously the acid gases and the formation water, considered as two pollutants.
Pan Canadian Limited's formation water and acid gas reinjection process, whose main stages are summed up hereafter and described in FIG. 1, is based on this principle.
The fluid coming from production wells is split into an oil phase which is recovered, an aqueous phase and a gas phase circulating respectively in lines 1 and 2. The aqueous phase is stored in atmospheric tanks 3, whereas the gas phase containing the acid gases is processed in an amine treating plant 4 in order to obtain a gas without acid components and a gas with a high acid component content at a pressure close to the atmospheric pressure. The gas fraction rich in acid gases is sent to a compressor 5 and the formation water is sent to a single-phase pump 6. The gas and the formation water, which have separately reached a given pressure level, are then mixed together in a mixer 7. Mixing is performed at a high pressure in order to facilitate dissolution of the gases in the water, the amount of dissolved acid gases increasing with the pressure level. This mixture occurring in the liquid form is then reinjected for example into an underground reservoir by means of a single-phase pump 8 suited to pump liquid single-phase fluids. Upstream from the high-pressure pump, the gas must be entirely dissolved in the liquid and the NPSHA (suction head available in relation to the vapor pressure of the gas) must also be higher than the NPSHR (suction head required at the pump inlet in relation to the vapour pressure).
In the case of high reinjection pressure applications and for production fluids with a high gas content, mixing of the water and of the gas is performed in successive separate pumping, compression and mixing stages.
This process requires equipment which has the drawback of being heavy and expensive, using both single-phase pumps and compressors, as well as many heat exchangers. Furthermore, as dissolution of the acid gases in the water is not instantaneous, it is necessary to use static or dynamic mixers in order to obtain perfect dissolution of the gas in the liquid upstream from the single-phase pumps, thus increasing even further the complexity of the materials, the cost and the overall dimensions of such a system.